Typically, each cell (single cell) has a low electromotive force. For example, a lithium-ion cell, which is known as a cell having a relatively high electromotive force, has an electromotive force that is only on the order of 4 V. Thus, in a case in which there is a need to provide a higher voltage, a cell module is known in which multiple cells are connected in series in the form of a module (see Patent document 1). Each typical cell as used here is configured as a flat, box-shaped cell. Such cells are connected in series to each other, so as to form a right-angled parallelepiped shaped cell stack.
A conventional cell module including such a cell stack is housed in a right-angled parallelepiped shaped holder formed of multiple frames, and is mounted on a mounting target such as a vehicle or the like. In a state in which such a cell module is housed in the holder, the cell stack is arranged such that each side of the right-angled parallelepiped cell stack is supported by a corresponding frame, and each surface of the right-angled parallelepiped cell stack is exposed to the exterior. The heat generated in the cell stack is released via heat exchange between the cell stack and the external air with which it is in contact.